Antipersonnel land mine



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ANTIPERSONNELLAND MINE Filed April 22, 1960 2 1 V/brati on 2 Defamat onres 90m vc mw ch.

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United States Patent 3,442,212 ANTIPERSONNEL LAND MINE Wesley Ferrell,Wayne, N.J., assignor, by mesne assignments, to the United States ofAmerica as represented by the Secretary of the Army Filed Apr. 22, 1960,Ser. No. 25,483 Int. Cl. F42b 23/26; F42c 13/06 US. Cl. 102l9.2 1 ClaimThis invention relates to antipersonnel land mines and more specificallyto land mines that can be laid with a high degree of safety and yet arevery sensitive to vibrations a short time after being laid.

A problem in the laying of land mines is to provide a mine which isentirely safe to handle when it is being laid and will remain safe for along enough period for the laying personnel to get clear of the area. Inconventional type mines the person who lays the mine removes a safetydevice such as a pin, wire or the like and the mine is then armed andready for detonation. It can thus be seen that if the mine is to besensitive for the purpose intended it is also dangerous to the layingpersonnel after having been armed.

The mine of the present invention overcomes the above noted deficienciesof conventional land mines. The mine of this invention is provided withan electrical arming means which has a time delay in the circuit. Whenpersonnel lay the mines they initiate the arming process. A charge isthen built up on a condenser and until this charge reaches the amountnecessary to operate the dctonator the mine is safe. By properlyselecting the components of the arming circuit this delay can be made tobe several minutes, thus giving the laying personnel ample time toretreat from the area. The detonator is operated by suitable means suchas a vibration responsive switch and it can be seen that this means canbe made as sensitive as desired Without endangering the layingpersonnel.

An object of this invention is to provide a land mine which is safe tolay and very sensitive after having been laid.

Another object of the invention is to provide a land mine with an armingmeans having a time delay.

Another object of the invention is to provide a land mine having anelectrical arming and detonating means with a time delay incorporatedtherein.

Yet another object of the invention is to provide a land mine in which adetonating charge is slowly built up on a condenser to provide a timedelay.

Still another object is to provide a land mine having a series ofcondensers in which a charge applied to the first is ultimately appliedafter a time delay to the last to provide a detonating charge.

These and other objects will become more apparent when reference is hadto the following detailed description and drawing in which:

FIGURE 1 is a schematic diagram of one form of my invention, and

FIGURE 2 is a schematic showing of a second embodiment of my invention.

With reference to FIGURE 1 there is shown a conventional, electricallyoperated land mine detonator 1. Connected in series with the detonatoris the vibration sensitive firing switch 2 which may be set at anydesired sensitivity. A firing condenser 3 is also connected as shownwith the switch and detonator and is adapted to store sufiicient energyto fire the detonator. The charge on the condenser 3 is built up by thebatteries 4 and 5 which are made of cells of low current capacity, suchas grid bias cells, for example Mallory type BC-S. The switch 6 isprovided between the batteries 4 and 5 and condenser 3 so that no chargecan be built up on the condenser until the switch is closed.

3,442,212 Patented May 6, 1969 When the mine is laid the switch 6 isclosed which applies a large capacitive load 3 across the battery cells4 and 5. Since these cells being of the grid bias type are designed as avoltage source at practically no current, the voltage falls rapidly andonly a minute current flows into the capacitor. The bias cells areinsufiicient to fire the detonator if connected directly thereto. Afterseveral minutes have elapsed the energy in the capacitor builds up tothe point where it will fire the detonator 1. It will be seen that untilthe charge builds up to this point operation of the vibration sensitiveswitch 2 would not be effective to detonate the mine. The delay involvedin building up the charge on capacitor 3 gives the laying personnelsufiicient time to retreat from the area before the mine is armed. Afterthe mine becomes activated and the capacitor is charged to cell voltagethe battery load becomes only the small leakage currents which occur inthe condenser. Thus, the mine will remain active until these leakagecurrents have exhausted the batteries. The length of time required forthe capacitor to obtain a full charge can be altered by battery design,condenser capacity or by adding resistance into the circuit. An exampleof the components contemplated for a known type detonator is a 50 tomicrofarad condenser and 1% volt grid bias cells in sufficient number toprovide the necessary voltage.

An alternative and preferred embodiment for electrically detonating aland mine and providing an arming time delay is illustrated in FIGURE 2.The mine detonator and vibration responsive firing switch are againindicated by reference numerals 1 and 2, respectively. Connected asshown with the detonator and switch is the firing condenser 7 andconnected in parallel with the condenser 7 are the condensers 8 and 9.The resistance 10 is connected between corresponding terminals ofcondensers 8 and 9 and the neon glow lamp 11 is connected betweencorresponding terminals of condensers 7 and 8. A pair of charging leadsare shown at 12 and 13 and are connected to a pair of pull out leads 114and 15, respectively, which are mounted on the pull out tab 16 mountedin housing 21. When the tab 16 is inserted the lead 15 is in electricalcontact with terminal 17 while the lead 14 is in electrical contact withterminals 18 and 19. It will be noted that terminals 17 and 18 areconnected across condenser 9 while the terminals 18 and 19 are connectedacross the condenser 7. The pull out tab 16 may be removed by means ofthe handle 20 thus disconnecting the leads 14 and 15 from terminals 17,18 and 19.

In the operation of the embodiment of FIGURE 2, just before the mine isto be laid a direct current potential is applied to the charging leads12 and 13. This is effective to charge the condenser 9 through thecontacts 17 and 18. When the mine is placed in position the pull out tab16 is removed. The charge placed on condenser 9 slowly leaks through theresistance 10 to accumulate on the condenser 8. The neon glow lamp 11acts as an automatic time delay switch, since it does not permit anycharge to pass through to firing condenser 7 until the dilference inpotential between condensers 7 and 8 is at least 21.6 volts Which is thefirst ionization potential of neon gas. When the potential differencebetween condensers 7 and 8 exceeds 21.6 volts the neon lamp will conductthe charge and the voltage on condenser 7 will rise. When the charge oncondenser 7 is equal to or greater than that required to fire thedetonator, the mine is armed and will fire on any slight disturbancewhich will close the switch 2.

It is to be noted that if the pull out tab 16 is not removed when thecondenser 9 is charged the mine cannot become armed. The lead wire .14shunts across terminals 18 and 19 and thus shunts condenser 7 preventingany charge from accumulating thereon. Thus, the device of FIGURE 2provides dual safety in the arming of the 3 mine. After the charge hasbeen applied to the leads 12 and 13 the mine cannot become armed untilthe tab 16 is removed, and after the tab- 16 is removed, there is asubstantial time delay until the charge appears on condenser 7.

It has been found that an arming time of three minutes is obtained withthe circuit of FIGURE 2 with a certain detonator and a charging voltageof 900 volts if the following components are used: Condensers 7, 8 and 9of 0.1, 0.05 and 0.1 microfarad capacity, respectively, and resistance10 of 10,000 megohm value.

I Wish it to be understood that I do not desire to be limited to theexact details of construction shOWn or described, for obviousmodifications will occur to a person skilled in the art.

I claim:

1. A land mine having delayed arming means including an electricallyactuated detonator, a vibration sensitive, normally open firing switchand a firing condenser connected in series in a closed circuit; armingmeans for said land mine comprising a second condenser connected inparallel with said first condenser; an ionizable gas discharge tubeconnected between corresponding terminals of said firing condenser andsaid second condenser; a third condenser connected in parallel with saidsecond condenser, a resistance connected between corresponding terminalsof said second and third condensers and in series with said dischargetube; and means for charging said third condenser when said mine is laidcomprising a housing of insulating material, first and second parallel,

spaced, pull-out electrical leads slidably mounted in said housing, apair of. electrical charging leads connected, one each, to the outerends of said pull-out leads, a tab of insulating material also fixed tothe outer ends of said pull-out leads, a first terminal slidablycontacting said second pull-out lead, and second and third terminalsslidably contacting said first pull-out lead, said first and secondterminals being connected across said third condenser and said secondand third terminals being connected across said firing condenser,whereby said mine is rendered safe until said pull-out leads areremoved.

References Cited UNITED STATES PATENTS 2,545,474 3/1951 Kurland et al.102-702 2,909,122 10/1959 Shoemaker et al. 102-702 2,943,569 7/1960Wolfe l02-16 2,981,190 4/1961 Will et a1 l02-70.2 3,011,096 11/1961Wallack et al. 10=270.2 X

FOREIGN PATENTS 1,056,970 5/1959 Germany.

VERLIN R. PENDEGRASS, Primary Examiner.

US. Cl. X.R.

1. A LAND MINE HAVING DELAYED ARMING MEANS INCLUDING AN ELECTRICALLYACTUATED DETONATOR, A VIBRATION SINSITIVE, NORMALLY OPEN FIRING SWITCHAND A FIRING CONDENSER CONNECTED IN SERIES IN A CLOSED CIRCUIT; ARMINGMEANS FOR SAID LAND MINE COMPRISING A SECOND CONDENSER CONNECTED INPARALLEL WITH SAID FIRST CONSENSER; AN IONIZABLE GAS DISCHARGE TUBECONNECTED BETWEEN CORRESPONDING TERMINALS OF SAID FIRING CONDENSER ANDSAID SECOND CONDENSER; A THIRD CONDENSER CONNECTED IN PARALLEL WITH SAIDSECOND CONDENSER, A RESISTANCE CONNECTED BETWEEN CORRESPONDING TERMINALSOF SAID SECOND AND THIRD CONDENSERS AN IN SERIES WITH SAID DISCHARGETUBE; AND MEANS FOR CHARGING SAID THIRD CONDENSER WHEN SAID MINE IS LAIDCOMPRISING A HOUSING OF INSULATING MATERIAL, FIRST AND SECOND PARALLELSPACED, PULL-OUT ELECTRICAL LEADS SLIDABLY MOUNTED IN SAID HOUSING, APAIR OF ELECTRICAL CHARGING LEADS CONNECTED, ONE EACH, TO THE OUTER ENDSOF SAID PULL-OUT LEADS, A TAB OF INSULATING MATERIAL ALSO FIXED TO THEOUTER CONTACTING SAID PULL-OUT LEADS, A FIRST TERMINAL SLIDABLYCONTACTING SAID SECOND PULL-OUT LEAD, AND SECOND AND THIRD TERMINALSSLIDABLY CONTACTING SAID FIRST PULL-OUT LEAD, SAID FIRST AND SECONDTERMINALS BEING CONNECTED ACROSS SAID THIRD CONDENSER AND SAID SECONDAND THRID TERMINALS BEING CONNECTED ACROSS SAID FIRING CONDENSER,WHEREBY SAID MINE IS RENDERED SAFE UNITL SAID PULL-OUT LEADS AREREMOVED.